TrigOutputHandling: clang-tidy suggestions and small improvements

Apply a set of small changes and slight refactoring of the code driven mainly by clang-tidy warnings.

There's a lot of changes, but mostly trivial.

The addressed warnings (not always all cases, only where reasonable):

• use = default to define a trivial destructor [modernize-use-equals-default]
• use using instead of typedef [modernize-use-using]
• implicit conversions of pointers to bool [readability-implicit-bool-conversion]
• implicit conversion from bool to char [readability-implicit-bool-conversion]
• pass by value and use std::move [modernize-pass-by-value]
• use nullptr [modernize-use-nullptr]
• all parameters should be named in a function [readability-named-parameter]
• implement the "rule of five" for BareDataBucket [cppcoreguidelines-special-member-functions]
• implement the "rule of zero" for TriggerEDMSerialiserTool::Address
• local copy of a variable never modified -> avoid the copy [performance-unnecessary-copy-initialization]
• some methods could be made static member functions or anonymous-namespace functions [readability-convert-member-functions-to-static]
• constructor does not initialize some fields [cppcoreguidelines-pro-type-member-init]
• use empty() instead of size()==0 [readability-container-size-empty]
• some improvements to memory allocation, avoid new if possible [cppcoreguidelines-owning-memory]
• do not use 'else' after 'return' [readability-else-after-return]
• function has a definition with different parameter names [readability-inconsistent-declaration-parameter-name]
• use a const reference instead of copy as loop variable [performance-for-range-copy]
• use dynamic_cast instead of static_cast to downcast from a base to a derived class [cppcoreguidelines-pro-type-static-cast-downcast]
• use single-character overload of string::find when searching for a single character [performance-faster-string-find]
• const values in declarations do not affect the signature of a function, so they should not be put there [readability-avoid-const-params-in-decls]